The invention relates to a lens shutter camera, and more particularly, to such a camera having a distance adjusting mechanism which causes a taking lens to move in the direction of an optical axis by means of a drive source such as motor, and also having a lens shutter mechanism for opening and closing shutter blades disposed within a barrel associated with the taking lens.
In the prior art, a distance adjusting mechanism which performs a distance adjustment of a camera by utilizing a motor is constructed in a manner such that the motor is maintained in coupled relationship with a distance ring through a gearing. Hence, a position assumed by the distance ring and corresponding to a selected distance is uniquely determined by the angular position where the motor stops. Such a mechanism is liable to malfunctioning, and since the motor is maintained in operative coupling with the distance adjustment, it cannot be freely utilized for other operations such as a shutter operation, for example.
As an alternative, distance adjusting means may include a detent pawl which leaves the distance ring at a selected position corresponding to a desired distance after the ring has been driven to such location by the motor, while releasing the motor. However, to change the distance setting, the engagement between the pawl and ring must be released, requiring a complex mechanism which adds to the space requirement of a camera. Also, a malfunctioning is frequently caused.
In the prior art, a lens shutter mechanism is known which is controlled for opening and closing by a self-charging operation. A mechanism of this type involves an increased stroke and requires an increased force for the depression of a shutter release. While a variety of proposals have been made to facilitate a shutter operation by utilizing a motor, it is essential when operating the shutter with the motor that the motor be fed with a constant voltage to maintain a constant speed of rotation and that a rapid shutter closing operation be enabled. The shutter opening operation may take place at a relatively slow rate of 30 m/sec, for example, and hence it is a simple matter to control the shutter opening by the rotation of the motor. However, it is difficult to achieve a very rapid shutter closing operation through the motor control in response to an exposure terminate signal. If the shutter closing operation is slowed, there results an error in the exposure period. The shorter the exposure period, the greater the magnitude of the error.
To effect a shutter charging operation after the shutter has been closed, a conventional lens shutter mechanism utilizing a motor requires the provision of an increased number of members or elements which are ganged with the motor and which must undergo a complicated operation with respect to the rotation of the motor.